Field of the Invention
The present invention relates to a next generation mobile communication.
Related Art
In 3GPP in which technical standards for mobile communication systems are established, in order to handle 4th generation communication and several related forums and new technologies, research on Long Term Evolution/System Architecture Evolution (LTE/SAE) technology has started as part of efforts to optimize and improve the performance of 3GPP technologies from the end of the year 2004
SAE that has been performed based on 3GPP SA WG2 is research regarding network technology that aims to determine the structure of a network and to support mobility between heterogeneous networks in line with an LTE task of a 3GPP TSG RAN and is one of recent important standardization issues of 3GPP. SAE is a task for developing a 3GPP system into a system that supports various radio access technologies based on an IP, and the task has been carried out for the purpose of an optimized packet-based system which minimizes transmission delay with a more improved data transmission capability.
An Evolved Packet System (EPS) higher level reference model defined in 3GPP SA WG2 includes a non-roaming case and roaming cases having various scenarios, and for details therefor, reference can be made to 3GPP standard documents TS 23.401 and TS 23.402. A network configuration of FIG. 1 has been briefly reconfigured from the EPS higher level reference model.
FIG. 1 shows the configuration of an evolved mobile communication network.
An Evolved Packet Core (EPC) may include various elements. FIG. 1 illustrates a Serving Gateway (S-GW) 52, a Packet Data Network Gateway (PDN GW) 53, a Mobility Management Entity (MME) 51, a Serving General Packet Radio Service (GPRS) Supporting Node (SGSN), and an enhanced Packet Data Gateway (ePDG) that correspond to some of the various elements.
The S-GW 52 is an element that operates at a boundary point between a Radio Access Network (RAN) and a core network and has a function of maintaining a data path between an eNodeB 22 and the PDN GW 53. Furthermore, if a terminal (or User Equipment (UE) moves in a region in which service is provided by the eNodeB 22, the S-GW 52 plays a role of a local mobility anchor point. That is, for mobility within an E-UTRAN (i.e., a Universal Mobile Telecommunications System (Evolved-UMTS) Terrestrial Radio Access Network defined after 3GPP release-8), packets can be routed through the S-GW 52. Furthermore, the S-GW 52 may play a role of an anchor point for mobility with another 3GPP network (i.e., a RAN defined prior to 3GPP release-8, for example, a UTRAN or Global System for Mobile communication (GSM) (GERAN)/Enhanced Data rates for Global Evolution (EDGE) Radio Access Network).
The PDN GW (or P-GW) 53 corresponds to the termination point of a data interface toward a packet data network. The PDN GW 53 can support policy enforcement features, packet filtering, charging support, etc. Furthermore, the PDN GW (or P-GW) 53 can play a role of an anchor point for mobility management with a 3GPP network and a non-3GPP network (e.g., an unreliable network, such as an Interworking Wireless Local Area Network (I-WLAN), a Code Division Multiple Access (CDMA) network, or a reliable network, such as WiMax).
In the network configuration of FIG. 1, the S-GW 52 and the PDN GW 53 have been illustrated as being separate gateways, but the two gateways may be implemented in accordance with a single gateway configuration option.
The MME 51 is an element for performing the access of a terminal to a network connection and signaling and control functions for supporting the allocation, tracking, paging, roaming, handover, etc. of network resources. The MME 51 controls control plane functions related to subscribers and session management. The MME 51 manages numerous eNodeBs 22 and performs conventional signaling for selecting a gateway for handover to another 2G/3G networks. Furthermore, the MME 51 performs functions, such as security procedures, terminal-to-network session handling, and idle terminal location management.
The SGSN handles all packet data, such as a user's mobility management and authentication for different access 3GPP networks (e.g., a GPRS network and an UTRAN/GERAN).
The ePDG plays a role of a security node for an unreliable non-3GPP network (e.g., an I-WLAN and a Wi-Fi hotspot).
As described with reference to FIG. 1, a terminal (or UE) having an IP capability can access an IP service network (e.g., IMS), provided by a service provider (i.e., an operator), via various elements within an EPC based on non-3GPP access as well as based on 3GPP access.
Furthermore, FIG. 1 shows various reference points (e.g., S1-U and S1-MME). In a 3GPP system, a conceptual link that connects two functions that are present in the different function entities of an E-UTRAN and an EPC is called a reference point. Table 1 below defines reference points shown in FIG. 1. In addition to the reference points shown in the example of Table 1, various reference points may be present depending on a network configuration.
TABLE 1REFERENCEPOINTDESCRIPTIONS1-MMEA reference point for a control plane protocol between the E-UTRAN and theMMES1-UA reference point between the E-UTRAN and the S-GW for path switchingbetween eNodeBs during handover and user plane tunneling per bearerS3A reference point between the MME and the SGSN that provides theexchange of pieces of user and bearer information for mobility between 3GPPaccess networks in idle and/or activation state. This reference point can beused intra-PLMN or inter-PLMN (e.g. in the case of Inter-PLMN HO).S4A reference point between the SGW and the SGSN that provides relatedcontrol and mobility support between the 3GPP anchor functions of a GPRScore and the S-GW. Furthermore, if a direct tunnel is not established, thereference point provides user plane tunneling.S5A reference point that provides user plane tunneling and tunnel managementbetween the S-GW and the PDN GW. The reference point is used for S-GWrelocation due to UE mobility and if the S-GW needs to connect to a non-collocated PDN GW for required PDN connectivityS11A reference point between the MME and the S-GWSGiA reference point between the PDN GW and the PDN. The PDN may be apublic or private PDN external to an operator or may be an intra-operatorPDN, e.g., for the providing of IMS services. This reference pointcorresponds to Gi for 3GPP access.
<Next Generation Mobile Communication Network>
Thanks to the success of LTE (Long Term Evolution) and LTE-Advanced (LTE-A) for 4G mobile communication, interest in the next generation, namely 5G mobile communication increases and thus study on the 5G mobile communication is progressing.
The 5th generation mobile telecommunications defined by the International Telecommunication Union (ITU) refers to communication providing a data transmission rate of up to 20 Gbps and an actual minimum transmission rate of at least 100 Mbps anywhere. The official name of the 5th generation mobile telecommunications is ‘IMT-2020’ and ITU's goal is to commercialize the ‘IMT-2020’ worldwide by 2020.
The ITU proposes three usage scenarios, for example, enhanced Mobile Broadband (eMBB), massive Machine Type Communication (mMTC) and Ultra Reliable and Low Latency Communications (URLLC).
First, the URLLC relates to a usage scenario requiring high reliability and low latency. For example, services such as automatic driving, factory automation, augmented reality require high reliability and low latency (e.g., a delay time of less than 1 ms). The delay time of current 4G (LTE) is statistically 21 to 43 ms (best 10%) and 33 to 75 ms (median). This is insufficient to support a service requiring a delay time of 1 ms or less.
Next, the eMBB usage scenario relates to a usage scenario requiring mobile ultra-wideband.
It seems difficult for this ultra-wideband high-speed service to be accommodated by the core network designed for legacy LTE/LTE-A.
Therefore, in the so-called fifth generation mobile communication, a redesign of the core network is urgently required.
FIG. 2 is an exemplary diagram illustrating a predicted structure of a next generation mobile communication in terms of a node.
Referring to FIG. 2, the UE is connected to a data network (DN) through a next generation RAN (Radio Access Network).
The Control Plane Function (CPF) node shown in FIG. 3 may perform all or a part of the MME (Mobility Management Entity) function of the fourth generation mobile communication, and all or a part of the control plane function of the Serving Gateway (S-GW) and the PDN-gateway (P-GW) of the fourth generation mobile communication. The CPF node includes an Access and Mobility Management Function (AMF) node and a Session Management Function (SMF) node.
The user plane function (UPF) node shown in the figure is a type of a gateway over which user data is transmitted and received. The UPF node may perform all or part of the user plane functions of the S-GW and the P-GW of the fourth generation mobile communication.
The PCF (Policy Control Function) node shown in FIG. 2 is configured to control a policy of the service provider.
The illustrated Application Function (AF) node refers to a server for providing various services to the UE.
The Unified Data Management (UDM) node as shown refers to a type of a server that manages subscriber information, like an HSS (Home Subscriber Server) of 4th generation mobile communication. The UDM node stores and manages the subscriber information in the Unified Data Repository (UDR).
The Authentication Server Function (AUSF) node as shown authenticates and manages the UE.
The Network Slice Selection Function (NSSF) node as shown refers to a node for performing network slicing as described below.
FIG. 3a is an exemplary diagram illustrating an architecture for supporting a multiple PDU session through two data networks. FIG. 3b is an exemplary diagram illustrating an architecture for supporting a concurrent access through two data networks.
FIG. 3a illustrates an architecture that allows an UE to simultaneously access two data network using a multiple PDU session. Two SMFs may be selected for two different PDU sessions.
FIG. 3b illustrates an architecture that allows the UE to simultaneously access two data networks using one PDU session.
<Network Slice>
The following describes the slicing of the network to be introduced in the next generation mobile communication.
Next-generation mobile communication introduces the concept of network slicing in order to provide various services through a single network. In this connection, slicing a network refers to a combination of network nodes with the functions needed to provide a specific service. The network node that constitutes the slice instance may be a hardware independent node, or it may be a logically independent node.
Each slice instance may consist of a combination of all the nodes needed to construct the entire network. In this case, one slice instance alone may provide service to the UE.
Alternatively, the slice instance may consist of a combination of some of the nodes that make up the network. In this case, the slice instance may provide service to the UE in association with other existing network nodes without the slice instance alone providing the service to the UE. In addition, a plurality of slice instances may cooperate with each other to provide the service to the UE.
The slice instance may differ from a dedicated core network in that all network nodes, including the core network (CN) node and the RAN may be separated from each other. Further, the slice instance differs from the dedicated core network in that the network nodes may be logically separated.
<Roaming in Next Generation Mobile Communication Network>
Meanwhile, there are two schemes for handling a signaling request from the UE in a situation where the UE roams in a visited network, for example, Visited Public Land Mobile Network (VPLMN). A local break out (LBO) being a first scheme handles a signaling request from the UE by a visited network. According to a Home Routing (HR) being a second scheme, the visited network transfers a signaling request from the UE to a home network of the UE.
FIG. 4a is an exemplary diagram illustrating an architecture to which the LBO scheme is applied during roaming. FIG. 4b is an exemplary diagram illustrating an architecture to which the HR scheme is applied during roaming.
As shown in FIG. 4a, in an architecture to which the LBO scheme is applied, user data are transferred to a data network in a VPLMN. To this end, a PCF in the VPLMN performs interaction with an AF in order to generate a PCC rule for a service in the VPLMN. A PCF node in the VPLMN creates a PCC rule based on a policy set insided according to a roaming convention with a Home Public Land Mobile Network (HPLMN) businessman.
As shown in FIG. 4b, in the architecture to which the HR scheme is applied, data of the UE is transferred to a data network in the HPLMN.
<Data Bypass to Non-3GPP Network>
In the next generation mobile communication, the data of the UE may bypass to a non-3GPP network, for example, a Wireless Local Area Network (WLAN) or Wi-Fi.
FIG. 5a to FIG. 5f illustrate architectures for bypassing data to the non-3GPP net work.
The Wireless Local Area Network (WLAN) or Wi-Fi is regarded as the untrusted non-3GPP network. In order to access the non-3GPP network to a core network, a Non-3GPP InterWorking Function (N3IWF) may be added.
<Interworking with Existing 4 Generation (G) Mobile Communication System>
Although the UE escapes from coverage of a next generation Radio Access Network (RAN), the UE may receive a service through a 4 G mobile communication system. The above refers to interworking. Hereinafter, the interworking will be described in detail.
FIG. 6a illustrates an architecture for interworking when the UE does not roam, and FIG. 6b illustrates an architecture for interworking when the UE roams.
Referring to FIG. 6a, when the UE does not roam, an E-UTRAN and an EPC for existing 4G LTE and a 5G mobile communication network may interwork with each other. In FIG. 6a, a Packet data network Gateway (PGW) for an existing EPC is divided into a PGW-U being responsible for only a user plane and a PGW-C being a control plane. Further, the PGW-U merges with an UPF of a 5G core network. The PGW-C merges with an SMF of the 5G core network. In addition, a Policy and Charging Rules Function (PCRF) for an existing EPC may merge with a PCF of the 5G core network. An HSS for the existing EPC may merge with an UDM of the 5G core network. Although the UE may access a core network through the E-UTRAN, the UE may access a core network through a radio access network (RAN) and an AMF.
Referring to FIG. 6a and FIG. 6b to compare with each other, when the UE roams a Visited Public Land Mobile Network (VPLMN), the data of the UE are transferred through a Home PLMN (HPLMN).
Meanwhile, an N26 interface shown in FIG. 6a and FIG. 6b is an interface connected between an MME and an AMF for easy interworking between an EPC and an NG. The N26 interface may be selectively supported according to a businessman. That is, for interworking with an EPC, a network businessman may provide an N26 interface or may not provide the N26 interface.
During a roaming situation, the UE transmits a PDU session establishment request message to the network. If the UE receives a response thereto, the UE may know that the PDU session is established. However, the UE cannot know whether the PDU session is established in a Local Breakout (LBO) scheme or a Home Routed (HR) scheme. Accordingly, the handover may not be performed. However, since the UE cannot know whether or not a real handover can succeed. In this case, unnecessary signaling occurs.